1. Technical Field
The present invention relates to a control circuit for an image-capturing device for calculating drive data for a focus adjustment member to compensate for movement of the image-capturing device on the basis of displacement velocity of the image-capturing device detected by a displacement velocity detector and position regarding the focus adjustment member of the image-capturing device detected by a position detector.
2. Background Art
Image-capturing devices, such as digital cameras or cameras mounted in cellular telephones, are increasingly equipped with a camera shake correction function to prevent a reduction in image quality due to camera shake. Various types of camera shake correction methods exist. In one method, an optical part, such as a correction lens or the like forming a focusing mechanism for image capture, or an image-capturing element, such as a CCD image sensor or the like, is displaced on the basis of vibration (angular velocity of the optical axis of the focusing mechanism) of the image-capturing device detected by a gyro sensor or the like. For position control of the focusing mechanism, it is necessary to detect the position of the member to be displaced, and for this position detection a Hall sensor or the like is employed.
To displace the correction lens or the like, an integration process of an angular velocity signal output from a gyro sensor is performed and conversion from angular velocity to an amount of displacement corresponding to angle is performed. This signal processing utilizes common digital data processing and the processing, such as integration, is performed after digital data conversion by an A/D converter (ADC: Analog-to-Digital Converter) of the signal from the sensor. Furthermore, to obtain a signal for controlling the actual drive of the correction lens or the like, a position detection signal from a Hall sensor is also necessary and the output of the Hall sensor is also subjected to A/D conversion, and then processed as digital data.
Then, drive data for the correction lens or the like obtained in this manner is converted to an analog signal by a D/A converter (DAC: Digital-to-Analog Converter) and supplied to an actuator for driving the correction lens. Furthermore, when the actuator is to be controlled using pulse-width modulation (PWM), digital data is supplied to a PWM modulation circuit and the actuator is controlled using PWM by this PWM circuit.